CORS README
Welcome to the National Oceanic and Atmospheric Administration's (NOAA)
Continuously Operating Reference Station (CORS) Network
http://www.ngs.noaa.gov/CORS
http://alt.ngs.noaa.gov/CORS
Last Updated: 6 September 2011
CONTENTS OF THIS FILE
======================
INTRODUCTION
ACCESS TO DATA
DIRECTORY STRUCTURE OF FTP SITE
BRIEF DESCRIPTION OF MAIN DIRECTORIES
DETAILED DESCRIPTION OF THE CONTENTS OF THE DIRECTORY coord
DETAILED DESCRIPTION OF THE CONTENTS OF THE DIRECTORY rinex
FILE RETENTION POLICY
CONTACT INFORMATION
INTRODUCTION
============
NOAA's National Geodetic Survey (NGS) operates the Continuously Operating
Reference Station (CORS) network that consists of group of Global Navigation
Satellite System (GNSS) reference stations which provide code range and carrier
phase data to users in support of postprocessing applications. The stations are
owned and operated by federal, state, local agencies, private companies, and
university groups, and NGS redistributes their data to the public free of charge.
The GNSS data collected at these stations are made available to the public by NGS
in Receiver INdependent EXchange (RINEX) format. The data include observation,
meteorological, navigation/ephemeris, station logs and NGS coordinate files for
the stations. Most data are available within 1 hour from when they were recorded
at the remote site, and a few sites have a delay of 24 hours.
All data since 9 February (040) 1994 are available.
ACCESS TO DATA
=================
Data can be retrieved via anonymous ftp from
cors.ngs.noaa.gov or alt.ngs.noaa.gov
or
ftp://www.ngs.noaa.gov/cors
or
ftp://alt.ngs.noaa.gov/cors
Alternatively a customized data request service is available at:
http://www.ngs.noaa.gov/UFCORS
DIRECTORY STRUCTURE OF FTP SITE
=================================
All characters within {} refer to variable names. For an explanation of these
please see next section EXPLANATION OF DIRECTORY CONTENTS
|
|
|--coord--|--coord_{yy}--|--{ssss} (individual sites)
| |--nad_geo.txt
| |--nad_xyz.txt
| |--itrf_geo.txt
| |--itrf_xyz.txt
| |
| |--Old--|{ssss}.{yy}{Mmm}{dd}
| |
| | for coord_08 file names have changed
| |--{ssss}_08.coord.txt (individual sites)
| |
| | composite coordinate files
| |--igs08_geo.comp.txt
| |--igs08_xyz.comp.txt
| |--igs08_geo.htdp.txt
| |--igs08_xyz.htdp.txt
| |--nad83_2011_geo.comp.txt
| |--nad83_2011_xyz.comp.txt
| |--nad83_2011_geo.htdp.txt
| |--nad83_2011_xyz.htdp.txt
| |--nad83_MA11_geo.comp.txt
| |--nad83_MA11_xyz.comp.txt
| |--nad83_MA11_geo.htdp.txt
| |--nad83_MA11_xyz.htdp.txt
| |--nad83_PA11_geo.comp.txt
| |--nad83_PA11_xyz.comp.txt
| |--nad83_PA11_geo.htdp.txt
| |--nad83_PA11_xyz.htdp.txt
|
|
|--Plots--|--{ssss}_08.60day.png (60-day plots of daily positions)
| |
| |--Longterm--|--{ssss}_08.longterm.png (longterm plots of
| | daily positions)
|
|
|-- README.txt (This file)
|-- RINEX-2.txt (RINEX 2 definition file)
|
| | | | |--{ssssdddh}.{yyt}.Z
| |--{yyyy}--|--{ddd}--|--{ssss}--|--{ssssdddh}.{yyt}.gz
|--rinex --| | | |--{ssssdddh}.{yy}S
| | | | |--{ssssdddh}.{yy}m.Z
--cors--| |
| | Orbit files
| |--brdc{ddd}0.{yy}n.gz
| |--igs{wwwwd}.{yy}.sp3.gz
| |--igr{wwwwd}.{yy}.sp3.gz
| |--igu{wwwwd}_{hh}.{yy}.sp3.gz
| |
| |
| |--sum_gz--|--{ssssdddh}.{yy}S
| |
|
|
| |
|--station_log--|--{ssss}.log.txt
| |
|
|--tst_gnssrnx-- test subdirectories
|
|--UFCORS.txt
|
BRIEF DESCRIPTION OF MAIN DIRECTORIES
==================================
coord NAD 83, IGS08, and ITRF coordinates and velocities for each
CORS site (see next section for a description of the files
and their formats)
Plots 60-day time series plots of CORS sites. These files
show the difference between the calculated daily position
and the published coordinate listed in the coord file for the
previous 60 days.
Long-term time seris plots derived from our "multiyear"/MYCS1
project.
rinex RINEX data files, orbit files
(see next section for a description of the files and their
formats)
station_log Station information, including current and historical
equipment used at a site.
File format {ssss}.log.txt
Where ssss - 4-character site id
tst_gnssrnx Test data sets not for operational use
DETAILED DESCRIPTION OF THE CONTENTS OF THE DIRECTORY coord
=========================================
For detailed explanation of these files and their formats see:
http://geodesy.noaa.gov/CORS/coords.shtml
in /cors/coord the following are available
Directories:
coord_{yy} where yy is a 2-digit year that corresponds to a particular
Global reference frame. Currently NGS supports IGS08 which is located
in coord_08, prior to this NGS supported global frames in the International
Terrestrial Reference Frame (ITRF) e.g. in coord_00 any
ITRF coordinates are in ITRF2000.
Within each directory up to 6 types of files are present:
With the introduction of IGS08 directory file naming changed:
In the directory coord08
{ssss}_08.coord.txt - is the coordinate file that contains the
current IGS08 and NAD 83(2011,MA11,PA11) xyz and
geographic coordinates for a particular site
Old/{ssss}.{yy}{Mmm}{dd} - are older coordinate file that applies to the time
prior to the specified data ({yy}{Mmm}{dd})
ssss - 4-character id
yy - 2-digit year
Mmm - 3-letter month
dd - 2-digit day of month
The following files are a composite listing of all CORS including
decommissioned sites.
igs08_geo_comp.txt - coordinates are computed IGS08 geographic coordinates
igs08_geo_htdp.txt - coordinates are modeled IGS08 geographic coordinates
igs08_xyz.comp.txt - coordinates are computed IGS08 xyz coordinates
igs08_xyz.htdp.txt - coordinates are modeled IGS08 xyz coordinates
nad83_2011_geo.comp.txt - coordinates are NAD_83(2011) computed geographic coordinates
nad83_2011_geo.htdp.txt - coordinates are NAD_83(2011) modeled geographic coordinates
nad83_2011_xyz.comp.txt - coordinates are NAD_83(2011) computed xyz coordinates
nad83_2011_xyz.htdp.txt - coordinates are NAD_83(2011) modeled xyz coordinates
nad83_MA11_geo.comp.txt - coordinates are NAD_83(MA11) computed geographic coordinates
nad83_MA11_geo.htdp.txt - coordinates are NAD_83(MA11) modeled geographic coordinates
nad83_MA11_xyz.comp.txt - coordinates are NAD_83(MA11) computed xyz coordinates
nad83_MA11_xyz.htdp.txt - coordinates are NAD_83(MA11) modeled xyz coordinates
nad83_PA11_geo.comp.txt - coordinates are NAD_83(PA11) computed geographic coordinates
nad83_PA11_geo.htdp.txt - coordinates are NAD_83(PA11) modeled geographic coordinates
nad83_PA11_xyz.comp.txt - coordinates are NAD_83(PA11) computed xyz coordinates
nad83_PA11_xyz.htdp.txt - coordinates are NAD_83(MA11) modeled xyz coordinates
In the directories coord94, coord96, coord97, coord00 the following files
may be found:
{ssss} - is the coordinate file that contains the current ITRF and NAD3
xyz and geographic coordinates and velocities for a particular
site
Old/{ssss}.{yy}{Mmm}{dd} - are older coordinate file that applies to the time
prior to the specified data ({yy}{Mmm}{dd})
ssss - 4-character id
yy - 2-digit year
Mmm - 3-letter month
dd - 2-digit day of month
The following files are a composite listing of all CORS including
decommissioned sites.
itrf_geo.txt - coordinates are ITRF geographic coordinates
itrf_xyz.txt - coordinates are ITRF xyz coordinates
nad_geo.txt - coordinates are NAD83 geographic coordinates
nad_xyz.txt - coordinates are NAD83 xyz coordinates
DETAILED DESCRIPTION OF THE CONTENTS OF THE DIRECTORY rinex
=========================================
in /cors/rinex/yyyy/ddd the following orbit/ephemeris files are available
Global broadcast orbit:
brdc{ddd}0.{yy}n.gz - Global broadcast/navigation/ephemeris file gzip compressed
ddd - is 3-digit day-of-year
yy - is 2-digit year
These files are built cumulatively every hour till the end
of the day
High-precision orbits published by IGS:
For detailed information on IGS orbit products see
http://igscb.jpl.nasa.gov/components/prods.html
wwww - is the 4-digit GPS week
d - is the 1-digit GPS day 0-Sunday,...6-Saturday
hh - is the 2-digit hour 00,06,12,18
IGS ultrarapid orbits are produced every 6 hours
igu{wwww}{d}_{hh}.sp3.gz - IGS ultrarapid orbits in sp3 format gzip compressed
IGS rapid orbits are produced with a latency of approximately 18 hours
igr{wwww}{d}.sp3.gz - IGS rapid orbits in sp3c format gzip compressed
IGS final orbits are produced with a 14-16 day latency
igs{wwww}{d}.sp3.gz - IGS final orbits in sp3c format gzip compressed
Please note:
Prior to 2007-357 only IGS orbits are available
All orbits between 1994.001 to 2007-357 are from the IGS reprocessing solution
and are aligned with IGS05
All orbits between 2007-357 to 2011-106
All orbits after 2011-107 or 17 April 2011 are aligned to IGS08
in /cors/rinex/{yyyy}/{ddd}/{ssss} 1 or more of the following data files are available
{ssss}{ddd}{h}.{yy}{t}.{C}
ssss - is the 4-character site identifier
ddd - is a 3-digit day-of-year
h - for 1 hour long (60 minute duration) files this is a letter
a through x that corresponds to the start hour as shown below
00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23
a b c d e f g h i j k l m n o p q r s t u v w x
for 24 hour (daily) long files the number 0 (zero) is used
yy - is a 2-digit year
t - is the type of file. 6 types exist
d - is a RINEX observation file that has been decimated to a
sampling rate of 30 seconds and that is Hatanaka compressed
g - is a RINEX GLONASS navigation data file
m - is a RINEX meterological data file
n - is a RINEX GPS navigation data file
o - is a RINEX observation file with the receiver sampling rate
of 1, 5, 15, 30 seconds, after 30 days this file is
decimated to 30 seconds
S - is a summary file of the Hatanaka compressed file (type d.Z)
created using the TEQC software
C - is compression type
gz - gzip compression format
Z - UNIX compression format
in /cors/rinex/{yyyy}/{ddd}/sum_gz the following type of files are available
{ssss}{ddd}{h}.{yy}S
This is a summary file of the file (type o.gz) created using the TEQC
software
FILE RETENTION POLICY
======================
RINEX observation, meteorological, navigation and TEQC summary files:
Hourly files are only kept for 2 days
Daily files are kept permanently
However after 30 days the 24hr (daily) RINEX observation files that are gzipped
({ssss}{ddd}0.{yy}o.gz) are decimated to a 30 second sampling rate equivalent
to the {ssss}{ddd}0.{yy}d.Z
site specific GPS navigation files are only kept for sites that NGS submits to
the IGS network
Meteorological files are available only for sites with independent meteorological
sensors
After three years the second copy of the RINEX observation files that are gzipped
is removed i.e. file name {ssss}{ddd}0.{yy}o.gz
All orbit files are kept permanently
Coord files are updated as needed
Logs files are updated as needed
Plot files are updated daily (except files in the "long-term" directory that were
last updated end of 2003)
CONTACT INFORMATION
==================================
If you have questions about this file or about CORS in general please check
http://www.ngs.noaa.gov/cors
http://alt.ngs.noaa.gov/cors
or email ngs.cors at noaa.gov
